Question

我正在尝试使用四个着色器：顶点着色器（VS），曲面细分控制着色器（TCS），曲面细分评估着色器（TES）和片段着色器（FS）。

但是，当我尝试加载这些着色器时，我得到： enter image description here

这是最令人费解的，我已经花了几个小时试图解决它。但是，我看不到＆＃34; gl_Vertex＆＃34;在我的代码中的任何地方，所以我真的卡住了。我甚至不知道哪个着色器是问题。

这是我目前加载着色器的代码（它看起来很多，但它实际上只是重复代码而略有变化）：

public static int loadShaderPair(String vertexShaderLocation, String fragmentShaderLocation, String tesShaderLocation, String tesscontrolShaderLocation) {
    int shaderProgram = glCreateProgram();
    int vertexShader = glCreateShader(GL_VERTEX_SHADER);
    int fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    int tesscontrolShader = glCreateShader(GL40.GL_TESS_CONTROL_SHADER);
    int tesShader = glCreateShader(GL40.GL_TESS_EVALUATION_SHADER);
    StringBuilder vertexShaderSource = new StringBuilder();
    StringBuilder fragmentShaderSource = new StringBuilder();
    StringBuilder tesShaderSource = new StringBuilder();
    StringBuilder tesscontrolShaderSource = new StringBuilder();
    BufferedReader tesShaderFileReader = null;
    try {
        tesShaderFileReader = new BufferedReader(new FileReader(tesShaderLocation));
        String line;
        while ((line = tesShaderFileReader.readLine()) != null) {
            tesShaderSource.append(line).append('\n');
        }
    } catch (IOException e) {
        e.printStackTrace();
        return -1;
    } finally {
        if (tesShaderFileReader != null) {
            try {
                tesShaderFileReader.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }


    BufferedReader tesscontrolShaderFileReader = null;
    try {
        tesscontrolShaderFileReader = new BufferedReader(new FileReader(tesscontrolShaderLocation));
        String line;
        while ((line = tesscontrolShaderFileReader.readLine()) != null) {
            tesscontrolShaderSource.append(line).append('\n');
        }
    } catch (IOException e) {
        e.printStackTrace();
        return -1;
    } finally {
        if (tesscontrolShaderFileReader != null) {
            try {
                tesscontrolShaderFileReader.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    BufferedReader vertexShaderFileReader = null;
    try {
        vertexShaderFileReader = new BufferedReader(new FileReader(vertexShaderLocation));
        String line;
        while ((line = vertexShaderFileReader.readLine()) != null) {
            vertexShaderSource.append(line).append('\n');
        }
    } catch (IOException e) {
        e.printStackTrace();
        return -1;
    } finally {
        if (vertexShaderFileReader != null) {
            try {
                vertexShaderFileReader.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
    BufferedReader fragmentShaderFileReader = null;
    try {
        fragmentShaderFileReader = new BufferedReader(new FileReader(fragmentShaderLocation));
        String line;
        while ((line = fragmentShaderFileReader.readLine()) != null) {
            fragmentShaderSource.append(line).append('\n');
        }
    } catch (IOException e) {
        e.printStackTrace();
        return -1;
    } finally {
        if (fragmentShaderFileReader != null) {
            try {
                fragmentShaderFileReader.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }


    glShaderSource(vertexShader, vertexShaderSource);
    glCompileShader(vertexShader);
    if (glGetShaderi(vertexShader, GL_COMPILE_STATUS) == GL_FALSE) {
        System.err.println("Vertex shader wasn't able to be compiled correctly. Error log:");
        System.err.println(glGetShaderInfoLog(vertexShader, 1024));
        return -1;
    }
    glShaderSource(tesscontrolShader, tesscontrolShaderSource);
    glCompileShader(tesscontrolShader);
    if (glGetShaderi(tesscontrolShader, GL_COMPILE_STATUS) == GL_FALSE) {
        System.err.println("tesscontrol shader wasn't able to be compiled correctly. Error log:");
        System.err.println(GL11.glGetString(GL11.glGetError()));
        System.err.println(glGetShaderInfoLog(tesscontrolShader, 1024));
    }
    glShaderSource(fragmentShader, fragmentShaderSource);
    glCompileShader(fragmentShader);
    if (glGetShaderi(fragmentShader, GL_COMPILE_STATUS) == GL_FALSE) {
        System.err.println("Fragment shader wasn't able to be compiled correctly. Error log:");
        System.err.println(GL11.glGetString(GL11.glGetError()));
        System.err.println(glGetShaderInfoLog(fragmentShader, 1024));
    }
    glShaderSource(tesShader, tesShaderSource);
    glCompileShader(tesShader);
    if (glGetShaderi(vertexShader, GL_COMPILE_STATUS) == GL_FALSE) {
        System.err.println("Tessellation shader wasn't able to be compiled correctly. Error log:");
        System.err.println(glGetShaderInfoLog(tesShader, 1024));
        return -1;
    }
    glAttachShader(shaderProgram, vertexShader);
    glAttachShader(shaderProgram, tesShader);
    glAttachShader(shaderProgram, tesscontrolShader);
    glAttachShader(shaderProgram, fragmentShader);
    glLinkProgram(shaderProgram);
    if (glGetProgrami(shaderProgram, GL_LINK_STATUS) == GL_FALSE) {
        System.err.println("Shader program wasn't linked correctly.");
        System.err.println(GL11.glGetString(GL11.glGetError()));
        System.err.println(glGetProgramInfoLog(shaderProgram, 1024));
        System.exit(1);
        return -1;
    }
    glDeleteShader(vertexShader);
    glDeleteShader(fragmentShader);
    glDeleteShader(tesShader);
    glDeleteShader(tesscontrolShader);
    return shaderProgram;
}

以下是我的着色器： VS：

layout (location = 0) in vec3 Position_VS_in;
layout (location = 1) in vec2 TexCoord_VS_in;
layout (location = 2) in vec3 Normal_VS_in;

uniform mat4 gWorld;

out vec3 WorldPos_CS_in;
out vec2 TexCoord_CS_in;
out vec3 Normal_CS_in;

void main()
{
WorldPos_CS_in = (gWorld * vec4(Position_VS_in, 1.0)).xyz;
TexCoord_CS_in = TexCoord_VS_in;
Normal_CS_in = (gWorld * vec4(Normal_VS_in, 0.0)).xyz;
gl_Position = ftransform();
}

TCS：

// define the number of CPs in the output patch
 layout (vertices = 3) out;

uniform vec3 gEyeWorldPos;

// attributes of the input CPs
in vec3 WorldPos_CS_in[];
in vec2 TexCoord_CS_in[];
in vec3 Normal_CS_in[];

 // attributes of the output CPs
out vec3 WorldPos_ES_in[];
out vec2 TexCoord_ES_in[];
out vec3 Normal_ES_in[];

float GetTessLevel(float Distance0, float Distance1)
{
float AvgDistance = (Distance0 + Distance1) / 2.0;

if (AvgDistance <= 2.0) {
    return 10.0;
}
else if (AvgDistance <= 5.0) {
    return 7.0;
}
else {
    return 3.0;
}
}

void main()
{
// Set the control points of the output patch
TexCoord_ES_in[gl_InvocationID] = TexCoord_CS_in[gl_InvocationID];
Normal_ES_in[gl_InvocationID] = Normal_CS_in[gl_InvocationID];
WorldPos_ES_in[gl_InvocationID] = WorldPos_CS_in[gl_InvocationID];
// Calculate the distance from the camera to the three control points
float EyeToVertexDistance0 = distance(gEyeWorldPos, WorldPos_ES_in[0]);
float EyeToVertexDistance1 = distance(gEyeWorldPos, WorldPos_ES_in[1]);
float EyeToVertexDistance2 = distance(gEyeWorldPos, WorldPos_ES_in[2]);

// Calculate the tessellation levels
gl_TessLevelOuter[0] = GetTessLevel(EyeToVertexDistance1, EyeToVertexDistance2);
gl_TessLevelOuter[1] = GetTessLevel(EyeToVertexDistance2, EyeToVertexDistance0);
gl_TessLevelOuter[2] = GetTessLevel(EyeToVertexDistance0, EyeToVertexDistance1);
gl_TessLevelInner[0] = gl_TessLevelOuter[2];
}

TES：

layout(triangles, equal_spacing, ccw) in;

uniform mat4 gVP;
uniform sampler2D gDisplacementMap;
uniform float gDispFactor;

in vec3 WorldPos_ES_in[];
in vec2 TexCoord_ES_in[];
in vec3 Normal_ES_in[];

out vec3 WorldPos_FS_in;
out vec2 TexCoord_FS_in;
out vec3 Normal_FS_in;

vec2 interpolate2D(vec2 v0, vec2 v1, vec2 v2)
{
return vec2(gl_TessCoord.x) * v0 + vec2(gl_TessCoord.y) * v1 + vec2(gl_TessCoord.z) * v2;
}

vec3 interpolate3D(vec3 v0, vec3 v1, vec3 v2)
{
return vec3(gl_TessCoord.x) * v0 + vec3(gl_TessCoord.y) * v1 + vec3(gl_TessCoord.z) * v2;
}

void main()
{  
// Interpolate the attributes of the output vertex using the barycentric coordinates
TexCoord_FS_in = interpolate2D(TexCoord_ES_in[0], TexCoord_ES_in[1], TexCoord_ES_in[2]);
Normal_FS_in = interpolate3D(Normal_ES_in[0], Normal_ES_in[1], Normal_ES_in[2]);
Normal_FS_in = normalize(Normal_FS_in);
WorldPos_FS_in = interpolate3D(WorldPos_ES_in[0], WorldPos_ES_in[1], WorldPos_ES_in[2]);
// Displace the vertex along the normal
float Displacement = texture(gDisplacementMap, TexCoord_FS_in.xy).x;
WorldPos_FS_in += Normal_FS_in * Displacement * gDispFactor;
gl_Position = gVP * vec4(WorldPos_FS_in, 1.0);
}

FS

varying vec4 position_in_view_space;
uniform sampler2D color_texture;

     void main()
     {
        float dist = distance(position_in_view_space, 
           vec4(0.0, 0.0, 0.0, 1.0));
        if (dist < 1000.0)
        {
            gl_FragColor = gl_Color;
              // color near origin
        }
        else
        {
        gl_FragColor = gl_Color;
           //kill;
           //discard;
           //gl_FragColor = vec4(0.3, 0.3, 0.3, 1.0); 
              // color far from origin
        }
     }

如果由于任何原因它有帮助，我的电脑支持最多（包括）OpenGL 4.0。

由于我无法弄清楚我是如何使用我不使用的一行代码，我希望你们中的一个能够诊断出这个问题。

Answer 1

嗯，错误信息很清楚，原因是：

layout (location = 0) in vec3 Position_VS_in;
[...]
gl_Position = ftransform();

ftransform是一个遗留函数，它使用遗留的bultin顶点位置属性gl_Vertex根据传统的bultin矩阵制服转换顶点。

GL规范还要求通用顶点属性0为旧内置gl_Vertex设置别名，因此您的属性索引0被阻止，您不能为此指定其他属性。

现在完全不清楚为什么在这里使用ftransform。好像你根本不想要那样。但我无法确定这一点。但它肯定不会那样工作。在我看来，你根本不应该使用那些被弃用的东西。

更新1

请注意，ftransform原则上等同于gl_ModelViewProjectionMatrix * gl_Vertex，gl_ModelViewProjectionMatrix是内置制服，代表您为P * MV设置的矩阵的乘积GL_PROJECTION GL_MODELVIEW使用已弃用的GL矩阵堆栈，gl_Vertex是使用glVertex... / glVertexPointer / glVertexAttribPointer(0,...)设置的内置顶点位置属性。两者都可以由用户定义的属性/制服替换。

ftransform的唯一转折是，对于相同的输入，它也保证获得与使用固定功能管道的渲染完全相同的结果。这对于多次传递算法很有用，其中一些传递需要使用着色器渲染，而其他算法使用固定功能管道。需要这样的函数，因为如果在没有着色器的情况下渲染时着色器不使用与GL实现完全相同的公式，则可能存在轻微的数值差异。

属性Position_VS_in绑定到通用属性0，但也使用gl_Vertex

1 个答案: